1. Field of the Invention
The present invention relates to a piston type compressor provided with a valve assembly for reducing noise, more particularly, to an improved piston type compressor wherein noise caused by a discharge or suction reed valve hitting a valve plate is reduced.
2. Description of the Related Art
A valve plate is generally disposed between each end face of a cylinder block and a front or rear housing in a piston type compressor such as a swash plate type or a wobble plate type compressor, and suction ports and discharge ports are formed in the valve plate corresponding to a suction chamber or a discharge chamber defined by the valve plate and the front or rear housing. A suction valve disk and a discharge valve disk are arranged respectively at each end face of the valve plate, these disks being provided with operable suction reed valves or operable discharge reed valves corresponding to the suction ports or the discharge ports.
Generally, a noise is caused when the valve plate made of metal is struck by the suction or discharge reed valves, or by a vibration of an valve assembly including the valve plate and the suction valve disk or the discharge valve disk. The following improvements are known as means for reducing such noise:
1: Forming a rubber coating on one end face of the valve plate corresponding to the suction valve disk or the discharge valve disk.
2: Forming a rubber coating on one end face of the suction valve disk or the discharge valve disk, facing the valve plate.
3: Mounting a rubber sheet, having substantially the same outward form as the valve plate, between the valve plate and the discharge valve disk.
4: Mounting a rubber sheet, having substantially the same outward form as the valve plate, between the valve plate and the suction valve disk.
In the above means, the impact energy when the valve plate is struck is absorbed by the rubber member, and thus the noise therefrom is reduced.
Nevertheless, the discharge reed valve or the suction reed valve strike the rubber member, and thus the rubber member is damaged or the layers constructing the member are exfoliated, and thus the reliability thereof is reduced.
Furthermore, a means for reducing a pressure generated in the elastic member (rubber member) when the valve is closed, i.e., reducing an opening area of the suction port or discharge port, or enlarging the size of the suction reed valve or discharge reed valve, has been disclosed in an attempt to solve the above-mentioned problem.
Another problem arises, however, in that the suction performance or discharge performance is reduced by an increase of the suction resistance or discharge resistance, and the suction temperature or discharge temperature is raised, when the former method is adopted. Further, another problem arises in that the energy loss becomes large during a suction or discharge process, due to an increase of a flexural rigidity of the suction reed valve or discharge reed valve, and the suction temperature r discharge temperature is raised, and this can lead to interference with other parts of the mechanism, when the latter method is adopted.